An apparatus and a method for measuring and monitoring the properties of a fluid, for example, pressure, temperature, and chemical properties, within a sample holder for an electron microscope. The apparatus includes at least one fiber optic sensor used for measuring temperature and/or pressure and/or pH positioned in proximity of the sample.

A sensor system for sensing pressure of a first fluid (e.g. a liquid and/or gas) comprises an optical sensing fiber that is configured for sensing pressure, and at least one sensor housing embedding the optical sensing fiber. The sensor housing is filled with a second fluid. The sensor housing comprises a non-hermetic pressure transfer medium comprised in the sensor system and positioned in the sensor housing such that a pressure of the first fluid can be transferred via the pressure transfer medium onto the second fluid towards the optical sensing fiber for determining based thereon a pressure of the first fluid.

A multiple sensor fiber optic sensing system includes an optical fiber having at least first fiber optic sensors and second fiber optic sensors deployed along its length. In response to an interrogating pulse, the first fiber optic sensors generate responses in a first optical spectrum window, and the second fiber optic sensors generate responses in a second, different optical spectrum window. The responses in the first optical spectrum window are measured in a first optical spectrum channel, and the responses in the second optical spectrum window are measure in a second, different optical spectrum channel and provide simultaneous indications of one or more parameters, such as temperature and pressure, in the environment in which the sensors are deployed.

An air pressure sensor based on a suspended-core fiber and a side-hole fiber is provided and includes a broadband light source, an optical fiber circulator, a sensing head and a spectrometer; the optical fiber circulator is connected with the broadband light source, the sensing head and the spectrometer; the sensing head includes a single mode fiber, a multimode fiber, the suspended-core fiber and the side-hole fiber; the single mode fiber is connected with the suspended-core fiber through the multimode fiber; and the multimode fiber is connected with the side-hole fiber through the suspended-core fiber. The sensor uses a fabrication method of fiber fusion, and the operation is simple; the sensor has advantages of small volume, compact structure and convenient use; the sensor has good stability without adhesive; additionally, parallel connection of double cavities could produce vernier effects, so the sensor has good contrast of interference spectrum and high sensitivity.

A pressure sensor includes: a light source that outputs signal light; a sensor optical fiber where the signal light is input and the signal light is propagated with a loss of 0.3 dB/m or more; and an optical receiver that receives the signal light propagated through the sensor optical fiber. Further, pressure applied to the sensor optical fiber is detected on a basis of intensity of the signal light received by the optical receiver.

A temperature correcting pressure gauge which has a diaphragm having at least one surface coupled to a source of pressure to be measured, the diaphragm first surface having a first FBG from a first optical fiber attached in an appropriately sensitive region of the diaphragm, a FBG from a second optical fiber attached to the opposite surface from the first FBG, the first and second FBGs reflecting or transmitting optical energy of decreasing or increasing wavelength, respectively, in response to an applied pressure. The first and second FBGs have nominal operating wavelength ranges that are adjacent to each other but are exclusive ranges and the FBGs also have closely matched pressure coefficients and temperature coefficients.

A biomedical pressure sensor for measuring the pressure in a fluid includes an optical fiber having at least one measurement section arranged at a distance from a distal end of the optical fiber. The biomedical pressure sensor further includes a deforming member on the outer surface of the optical fiber at the location of the measurement section that is arranged for locally deforming the optical fiber under the influence of the applied pressure of the fluid to be measured. The measurement section is arranged for measuring said local deformation of the optical fiber.

A method for forming a pressure sensor is provided wherein an optical fibre is provided, the optical fibre comprising a core, a cladding surrounding the core, and a birefringence structure for inducing birefringence in the core. The birefringence structure comprises first and second holes enclosed within the cladding and extending parallel to the core. A portion of the optical fibre comprising the core and the birefringence structure is encased within a chamber, wherein the chamber is defined by a housing comprising a pressure transfer element for equalising pressure between the inside and the outside of the housing. An optical sensor is provided along the core of the optical fibre. Providing the optical sensor comprises optically inducing stress in the core so that the optical sensor exhibits intrinsic birefringence. The chamber is filled with a substantially non-compressible fluid. Consequently, the birefringence structure is shaped so as to convert an external pressure provided by the non-compressible fluid within the chamber to an anisotropic stress in the optical sensor.

A system for measuring a flow rate of a fluid containing liquid includes a body in which the fluid flows, at least one rotor configured to be rotated by the fluid, and a device for measuring a rotation speed of the rotor. The measuring device includes an optical module configured to transmit an incident light radiation on vanes of the rotor, in a direction substantially perpendicular to an axis of rotation of the rotor and receive a reflected light radiation coming from the vanes. The measuring device further includes a conversion module configured to determine the rotation speed of the rotor according to the reflected light radiation and determine the flow rate of the fluid.

A passive microscopic Fabry-Pérot Interferometer (FPI) pressure sensor includes an optical fiber and a three-dimensional microscopic optical enclosure. The three-dimensional microscopic optical enclosure includes tubular side walls having lateral pleated corrugations and attached to a cleaved tip of the optical fiber to receive a light signal. An optically reflecting end wall is distally engaged to the tubular side walls to enclose a trapped quantity of gas that longitudinally positions the optically reflecting end wall in relation to ambient air pressure, changing a distance traveled by a light signal reflected back through the optical fiber.